Abstract: This paper studied the desilication and purification of magnetite reverse flotation using an organosilicon compound benzylaminoethylaminopropyldimethoxymethylsilane (TAS550) as a collector, and the action mechanism between the collector and minerals by FTIR analysis, contact angle, determination of adsorbing capacity, determination of Zeta potential. As shown by the result of the flotation study, TAS550 displayed excellent collection performance. Under the conditions of pH 8.0 and 2×10^-4 mol/L TAS550, the performance in collecting quartz and magnetite reached the optimal level. Their recovery rates were 98.21% and 79.13%, respectively. Using 400 mg/L starch as an inhibitor could effectively inhibit magnetite and had little impact on the recovery of quartz. The tests on the reverse flotation of quartz and magnetite under such a condition reached ideal indicators. The experiments on the determination of FTIR, Zeta potential, adsorbing capacity, and contact angle indicated the collector TAS550 was physical adsorption on the surface of quartz and effectively improved the hydrophobicity of the quartz surface.